Engine blew up, but what went first?

[jakk220]

OK so about a month ago I blew up my motor, had a hole in the oil pan and block and obviously knew what happened, I threw a rod. What I found when I went to pull the head to rebuild was some major carnage that i did not know existed. Lets start with my timing belt, which was missing about 15 or so teeth. Now I am thinking that it snapped a rod due to the timing belt shredding some teeth. But what really amazed me is what I seen next.

I threw another part of the rod through the other side of the block and actually broke my starter off of the engine and put a huge dent in it. Not to mention a nice hole in the cylinder wall. Pretty crazy if you ask me, but it gets better. After I pulled the head I looked at the back of the motor and saw the best part.

My balance shaft literally shot out of the block causing probably the biggest hole ever in a 4g63 . I have never heard of this happening so it sort of blew my mind. My question is.... what actually went first do you think? Timing belt? balance shaft? the rod? Feedback is appreciated and let me know what you think of the damage .

Pics coming up in just a second

timing belt gone.

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hole in front of block

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hole in cylinder wall

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snapped rod

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nice huge dent in starter which was not connected to the motor when i went to go take it off....it blew off

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the balance shaft...insane

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the piston

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[1997_GSX]

Your lucky when the starter broke off it didn't crack the bellhousing

 

[jakk220]

yeah I know. so far I've lucked out since the bell housing is not cracked and the head is salvageable except from some bent valves. It is at the machine shop now and I got a built motor going in.

 

[JusMX141]

Timing belt skipped, the oil pump went out of phase with the crank, the crank hit the balance shaft....bang. Junk.

 

[jakk220]

That's what i thought but I have a bunch of people saying "a timing belt / balance shaft belt wont cause a rod to snap"

 

[gofer]

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That block looks like swiss cheese, I couldn't imagine what that would have sounded like either. YIKES.

 

[JusMX141]

I hate to point out the obvious, but had you done a balance shaft elimination prior you'd be nursing a few bent valves right now instead of building a new engine.

 

[jakk220]

yea I know. But I honestly have not had the car that long and the timing belt was replaced like 30k miles ago...

 

[gofer]

Could it have gone something like this...

1. BS belt snapped and went into oil pump sprocket.
2. Oil pump froze.
3. Stripped teeth off the timing belt since the cam gears/crank were still turning it.
4. Crank/rod hit the balance shaft.
5. Block became swiss cheese

That would follow the story of a true DSM failure too. Leave it to the least expensive part on the engine to fail and create the most damage possible, a $10 belt lead to $1500+ worth of damage.

 

[jakk220]

That would make sense. For some reason to me its just crazy that the balance shaft shot out and my starter blew off . Stupid balance shafts. Now i got a gates racing timing belt and balance shaft belt so i think ill be better off with this next motor hopefully.

 

[WES_393]

That would make sense. For some reason to me its just crazy that the balance shaft shot out and my starter blew off . Stupid balance shafts. Now i got a gates racing timing belt and balance shaft belt so i think ill be better off with this next motor hopefully.

While you have the engine out, eliminate the blance shaft. It's a load easier with the engine out. Not to mention if you ever want to up the HP of your engine you'll need to get rid of it anyways. An aftermarket BS belt won't matter, the overall design is just a hazard to the entire engine (obviously).

You lost one engine from it, why risk it again?

 

[JusMX141]

Could it have gone something like this...

1. BS belt snapped and went into oil pump sprocket.
2. Oil pump froze.
3. Stripped teeth off the timing belt since the cam gears/crank were still turning it.
4. Crank/rod hit the balance shaft.
5. Block became swiss cheese

Welcome to post #4, jackass.

 

[jakk220]

To be completely honest, i thought they were a lot more expensive than they are. But now that i know that RRE has one for 60$ I might just have to get one.

 

[WES_393]

To be completely honest, i thought they were a lot more expensive than they are. But now that i know that RRE has one for 60$ I might just have to get one.

All you REALLY need is the stubby shaft. You could leave the front shaft in to block the oil passages and call it a day.

 

[jakk220]

do you know where i could just order the stubby shaft from?

 

[WES_393]

The part number for the stub shaft is MD098626

Here's where I got mine from.

Balance Shaft Elimination Kit (DSM/Evo) - Modern Automotive Performance

Just make sure you read up on all the ways people do it. You can leave the front shaft in, or flip the bearings, or buy block of bearings, etc etc. It's all up to how you want to do it, just make sure it's done right.